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The myeloproliferative neoplasms are associated with chronic kidney disease but whether clonal haematopoiesis of indeterminate potential (CHIP) is associated with impaired kidney function is unknown. In the Danish General Suburban Population Study (N = 19 958) from 2010 to 2013, 645 individuals were positive for JAK2V617F (N = 613) or CALR (N = 32) mutations. Mutation-positive individuals without haematological malignancy were defined as having CHIP (N = 629). We used multiple and inverse probability weighted (IPW)-adjusted linear regression analysis to estimate adjusted mean (95% confidence interval) differences in estimated glomerular filtration rate (eGFR; ml/min/1.73 m2) by mutation status, variant allele frequency (VAF%), blood cell counts, and neutrophil-to-lymphocyte ratio (NLR). We performed 11-year longitudinal follow-up of eGFR in all individuals. Compared to CHIP-negative individuals, the mean differences in eGFR were −5.6 (−10.3, −0.8, p =.02) for CALR, −11.9 (−21.4, −2.4, p = 0.01) for CALR type 2, and −10.1 (−18.1, −2.2, p =.01) for CALR with VAF ≥ 1%. The IPW-adjusted linear regression analyses showed similar results. NLR was negatively associated with eGFR. Individuals with CALR type 2 had a worse 11-year longitudinal follow-up on eGFR compared to CHIP-negative individuals (p =.004). In conclusion, individuals with CALR mutations, especially CALR type 2, had impaired kidney function compared to CHIP-negative individuals as measured by a lower eGFR at baseline and during 11-year follow-up.

Recent studies have shown the Philadelphia-negative myeloproliferative neoplasms (MPN) to be massively underdiagnosed and often preceded by a long pre-diagnostic phase of several years, in which many patients suffer serious vascular events. In this review, we focus on the urgent need for earlier diagnosis and treatment of MPN. Such efforts are foreseen to decrease morbidity and mortality for the individual patients and potentially reduce costs for health and social care systems.

There is mounting evidence that the immune system can spontaneously clear malignant lesions before they manifest as overt cancer, albeit this activity has been difficult to demonstrate in humans. The calreticulin (CALR) exon 9 mutations are driver mutations in patients with chronic myeloproliferative neoplasms (MPN), which are chronic blood cancers. The CALR mutations generate a neo-antigen that is recognized by patient T cells, and T cells isolated from a patient with a CALR-mutation can recognize and kill autologous CALR-mutant cells. Surprisingly, healthy individuals display frequent and strong T cell responses to the CALR neo-antigens too. Furthermore, healthy individuals display immune responses to all parts of the mutant CALR epitope, and the CALR neo-epitope specific responses are memory T cell responses. These data suggest that although healthy individuals might acquire a CALR mutation, the mutant cells can be eliminated by the immune system. Additionally, a small fraction of healthy individuals harbor a CALR exon 9 mutation. Four healthy individuals carrying CALR mutations underwent a full medical examination including a bone marrow biopsy after a median follow up of 6.2 years. None of these patients displayed any signs of CALR-mutant MPN. Additionally, all healthy individuals displayed strong CALR neo-epitope specific T cell responses suggesting that these healthy individuals retained their CALR-mutant cells in the editing stage for several years. Thus, we suggest that CALR-mutant MPN could be a disease model of cancer immuno-editing, as we have demonstrated that CALR-mutant MPN displays all three stages described in the theory of cancer immuno-editing.

The JAK2 V617F and calreticulin mutations (CALR) are frequent within myeloproliferative neoplasms (MPNs). JAK2 V617F has been detected in the general population, but no studies have previously investigated the CALR prevalence. Thus, we aimed to determine the CALR and JAK2 V617F population prevalence and assess the biochemical profile and lifestyle factors in mutation-positive individuals with and without MPN. 19 958 eligible participants, enrolled from 2010-2013, from the Danish General Suburban Population Study were screened for JAK2 V617F and CALR by droplet digital polymerase chain reaction with (3.2%) mutation positives of which 16 (2.5%) had MPN at baseline. Of 645 participants, 613 were JAK2 V617F positive, and 32 were CALR positive, corresponding to a population prevalence of 3.1% (confidence interval [CI], 2.8-3.3) and 0.16% (CI, 0.11-0.23), respectively. Increasing age, smoking, and alcohol were risk factors for the mutations. JAK2 V617F positives with and without MPN presented elevated odds for prevalent venous thromboembolism. The odds ratio for a diagnosis of MPN per percentage allele burden was 1.14 (95% CI, 1.09-1.18; P = 1.6 × 10−10). Mutation positives displayed higher blood cell counts than nonmutated participants, and 42% of mutation positives without MPN presented elevation of ≥1 blood cell counts; 80 (13%) even presented blood cell counts in accordance with current MPN diagnostic criteria. In conclusion, we present a novel population prevalence of CALR and a JAK2 V617F prevalence that is 3 to 30 times higher compared with less sensitive methods. Mutation-positive non-MPNs with elevated blood cell counts raise concerns of MPN underdiagnosis in the population.

Pegylated interferon-α (peg-IFNa) treatment induces molecular responses (MR) in patients with myeloproliferative neoplasms (MPNs), including partial MR (PMR) in 30–40% of patients. Here, we compared the efficacy of IFNa treatment in JAK2V617F- vs. calreticulin (CALR)-mutated cells and investigated the mechanisms of differential response. Retrospective analysis of MPN patients treated with peg-IFNa demonstrated that patients harboring the JAK2V617F mutation were more likely to achieve PMR than those with mutated CALR (p = 0.004), while there was no significant difference in hematological response. In vitro experiments confirmed an upregulation of IFN-stimulated genes in JAK2V617F-positive 32D cells as well as patient samples (peripheral blood mononuclear cells and CD34+ hematopoietic stem cells) compared to their CALR-mutated counterparts, and higher IFNa doses were needed to achieve the same IFNa response in CALR− as in JAK2V617F-mutant 32D cells. Additionally, Janus-activated kinase-1 (JAK1) and signal transducers and activators of transcription 1 (STAT1) showed constitutive phosphorylation in JAK2V617F-mutated but not CALR-mutated cells, indicating priming towards an IFNa response. Moreover, IFN-induced growth arrest was counteracted by selective JAK1 inhibition but enhanced by JAK2 inhibition. In conclusion, our data suggest that, clinically, higher doses of IFNa are needed in CALR-mutated vs. JAK2V617F-positive patients and we suggest a model of JAK2V617F-JAK1/STAT1 crosstalk leading to a priming of JAK2V617F-positive cells to IFNa resulting in differential sensitivity.

Somatic mutations in exon 9 of the calreticulin gene (CALR) are found in the majority of the JAK2V617F-negative Philadelphia-negative myeloproliferative neoplasms (MPNs), essential thrombocythemia ...

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Introduction: The Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are associated with driver mutations in JAK2, CALR, and MPL genes. Non-driver mutations involved in epigenetic regulation, signaling, and splicing are suggested to affect disease progression and treatment response. Interferon-alpha2 (IFN) induces hematologic and molecular responses in patients (pts) with MPNs. We studied 20 CALR positive pts by targeted next generation sequencing (NGS) of 68 genes and investigated the impact of somatic mutations on the molecular response to IFN. Methods: Twenty JAK2V617F negative CALR mutated pts (type 1 (n=14), type 2 (n=4), and other (n=2)) with ET (n=3), pre-PMF (n=5) and PMF (n=12) treated with IFN participated in the study. Targeted NGS was performed on DNA from peripheral blood at baseline and during IFN therapy. Libraries were prepared using an in-house gene panel covering 68 genes (Table 1). NGS was performed on the Ion Torrent platform and data were analyzed using Biomedical Genomics workbench and VarSeq. Variants with coverage 1% were excluded. A mutation with VAF 3% in the paired sample. Statistical analysis was done in R and a p-value Results: Mean average coverage per base was 2749 (range:1964-3874). In all pts, median CALR allele burden (%CALR) was 41.5% (range: 30-53) and 40% (range: 5.7-54) at baseline and follow-up, respectively. The median duration of IFN treatment from NGS at baseline to follow-up was 33 months (range: 7-100). Median number of non-driver mutations was 3 (range: 0-9) in all pts. Nineteen (95%) pts had at least one non-driver mutation, 14 (70%) >1, and 12 (60%) ³3. Stratified according to molecular response (MR) and non-MR, 4 (20%) achieved MR and 16 (80%) non-MR. Median %CALR at baseline was 42 (30-53) and 39 (33-49) in non-MR and MR, respectively, and 44 (25-54) and 10 (6-15) in non-MR and MR, respectively, during treatment with IFN. Median number of non-driver mutations was 2 (range: 0-6) in MR and 3 (range: 1-9) in non-MR. In all pts, there were 64 non-driver mutations in 18 genes at baseline and during IFN therapy. Of the 20 pts analyzed, TET2 occurred in 50% of pts, CUX1 in 45%, DNMT3A in 40%, GATA2 in 35%, ASXL1 in 30%, and SH2B3 in 10%. Each of the mutations - CBL, IKZF1, VEGFA and XPC occurred in 10% and EZH2, JAK2S523del, NF1, NFE2, PHIP, SF3B1, SRSF2, and TGFB1 in 5%. Interestingly, the epigenetic regulator genes ASXL1, DNMT3A, and TET2 were frequently mutated. Notably, TET2 occurred exclusively in pre-PMF and PMF. To examine if non-driver mutations were associated with a response to treatment with IFN, %CALR was evaluated in TET2, ASXL1, CUX1, DNMT3A, and GATA2 wild type (wt) and mutated pre- and post-treatment samples. Patients with mutations in CUX1 had a significantly higher post-IFN-treatment %CALR compared to CUX1 wt pts (p Discussion and Conclusions: In the present study, ASXL1, DNMT3A, and TET2 were frequently mutated possibly due to the high number of pts with pre-PMF and PMF. An association between poor response to IFN and ASXL1 mutations was recently reported in PMF. Indeed, we found a possible association between ASXL1 mutations and non-MR with increased or unchanged %ASXL1 during IFN therapy. However, in one MR and one non-MR, we recorded a marked decline in %ASXL1 but a sustained decrease or increase in %CALR, respectively. These results might imply a pt specific clonal heterogeneity. CUX1 is a transcription factor regulating TP53. We show that pts without CUX1 mutations had a significant reduction in %CALR and a significantly lower %CALR compared to CUX1 mutated pts during treatment. Our finding of a blunted response to IFN in CALR/CUX1 mutated pts deserves further studies in larger cohorts of CALR mutated MPNs. Disclosures Hasselbalch: Novartis: Research Funding.

PURPOSE: Secondary CNS involvement (SCNS) is a profoundly adverse complication of diffuse large B-cell lymphoma. Evidence from older series indicated a median overall survival (OS) < 6 months; however, data from the immunochemotherapy era are limited.METHODS: Patients diagnosed with SCNS during or after first-line immunochemotherapy were identified from databases and/or regional/national registries from three continents. Clinical information was retrospectively collected from medical records.RESULTS: In total, 291 patients with SCNS were included. SCNS occurred as part of first relapse in 254 (87%) patients and 113 (39%) had concurrent systemic relapse. With a median post-SCNS follow-up of 48 months, the median post-SCNS OS was 3.9 months and 2-year OS rate was 20% (95% CI: 15-25). In multivariable analysis of 173 patients treated with curative/intensive therapy (such as high-dose methotrexate [HDMTX] or platinum-containing regimens), age ≤60 years, performance status 0-1, absence of combined leptomeningeal and parenchymal involvement, and SCNS occurring after completion of first-line therapy were associated with superior outcomes. Patients ≤60 years with performance status 0-1 and treated with HDMTX-based regimens for isolated parenchymal SCNS had a 2-year OS of 62% (95% CI: 36-80). In patients with isolated SCNS, the addition of rituximab to HDMTX-based regimens was associated with improved OS. Amongst patients with isolated SCNS in CR following intensive treatment, high-dose chemotherapy and autologous stem cell transplantation did not improve OS (P = 0.9).CONCLUSIONS: In this large international cohort of patients treated with first-line immunochemotherapy, outcomes following SCNS remain poor. However, a moderate proportion of patients with isolated SCNS who received intensive therapies achieved durable remissions.

Philadelphia-negative myeloproliferative neoplasms (MPNs) are a diverse group of diseases whose common feature is the presence of V617F mutation of the JAK2 gene. In the era of novel therapeutic strategies in MPNs, such as JAK-inhibitor therapy, there is a growing need for establishing high sensitive quantitative methods, which can be useful not only at diagnosis but also for monitoring therapeutic outcomes, such as minimal residual disease (MRD). In this study, we compared the qPCR and ddPCR methods and their clinical utility for diagnosis, prognostication, and treatment monitoring of MPNs with JAK2 V617F mutation in 63 MPN patients of which 6 were subjected to ruxolitinib treatment. We show a high conformance between the two methods (correlation coefficient r = 0.998 (p

PURPOSE: Development of secondary central nervous system involvement (SCNS) in patients with diffuse large B-cell lymphoma is associated with poor outcomes. The CNS International Prognostic Index (CNS-IPI) has been proposed for identifying patients at greatest risk, but the optimal model is unknown.METHODS: We retrospectively analysed patients with diffuse large B-cell lymphoma diagnosed between 2001 and 2013, staged with PET/CT and treated with R-CHOP(-like) regimens. Baseline clinicopathologic characteristics, treatments, and outcome data were collected from clinical databases and medical files. We evaluated the association between candidate prognostic factors and modelled different risk models for predicting SCNS.RESULTS: Of 1532 patients, 62 (4%) subsequently developed SCNS. By multivariate analysis, disease stage III/IV, elevated serum LDH, kidney/adrenal and uterine/testicular involvement were independently associated with SCNS. There was a strong correlation between absolute number of extranodal sites and risk of SCNS; the 144 patients (9%) with >2 extranodal sites had a 3-year cumulative incidence of SCNS of 15.2% (95% confidence interval [CI] 9.2-21.2%) compared with 2.6% (95% CI 1.7-3.5) among those with ≤2 sites (P < 0.001). The 3-year cumulative risks of SCNS for CNS-IPI defined risk groups were 11.2%, 3.1% and 0.4% for high-, intermediate- and low-risk patients, respectively. All risk models analysed had high negative predictive values, but only modest positive predictive values.CONCLUSIONS: Patients with >2 extranodal sites or high-risk disease according to the CNS-IPI should be considered for baseline CNS staging. Clinical risk prediction models suffer from limited positive predictive ability, highlighting the need for more sensitive biomarkers to identify patients at highest risk of this devastating complication.

Involvement of the internal female reproductive organs by diffuse large B-cell lymphoma (DLBCL) is uncommon, and there are sparse data describing the outcomes of such cases. In total, 678 female patients with DLBCL staged with positron emission tomography/computed tomography and treated with rituximab-containing chemotherapy were identified from databases in Denmark, Great Britain, Australia, and Canada. Overall, 27/678 (4%) had internal reproductive organ involvement: uterus (n = 14), ovaries (n = 10) or both (n = 3). In multivariate analysis, women with uterine DLBCL experienced inferior progression-free survival and overall survival compared to those without reproductive organ involvement, whereas ovarian DLBCL was not predictive of outcome. Secondary central nervous system (CNS) involvement (SCNS) occurred in 7/17 (41%) women with uterine DLBCL (two patients with concomitant ovarian DLBCL) and 0/10 women with ovarian DLBCL without concomitant uterine involvement. In multivariate analysis adjusted for other risk factors for SCNS, uterine involvement by DLBCL remained strongly associated with SCNS (Hazard ratio 14·13, 95% confidence interval 5·09-39·25, P < 0·001). Because involvement of the uterus by DLBCL appears to be associated with a high risk of SCNS, those patients should be considered for CNS staging and prophylaxis. However, more studies are needed to determine whether the increased risk of secondary CNS involvement also applies to women with localized reproductive organ DLBCL.

INTRODUCTION Chronic inflammation has recently been proposed as the driving force for the development of the Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). Chronic inflammation is associated with various metabolic disturbances and may also contribute to the massive comorbidity burden in MPNs, which include e.g. inflammatory bowel diseases (Crohn's disease and ulcerative colitis) and polymyalgia rheumatica. Accordingly, MPNs have also been described as "inflammatory diseases". The metabolic syndrome has so far not been shown to be prevalent in patients with MPNs although the chronic inflammatory state might induce insulin resistance as in other chronic inflammatory diseases. If MPNs indeed are preceded by a chronic inflammatory drive eliciting persistent leukocytosis, monocytosis and thrombocytosis, and ultimately clonal myeloproliferation it is intriguing to consider if MPNs and metabolic syndrome share common pathways. If so, an MPN-phenotype might be expected to be associated with metabolic syndrome in the background population. Therefore, in this study, we tested the association between circulating inflammatory markers (CIMs), a phenotypical presentation of MPNs (e.g. erythrocytosis, leukocytosis, and thrombocytosis), and the metabolic syndrome in a general population study. METHODS Data sources In this cross-sectional study, we used data from 20,872 individuals from the Danish General Suburban Population Study (GESUS). Individuals were invited between January 2010 and October 2013 and data were collected through questionnaires, health examinations, and biochemical measurements. Analyses We analyzed eight CIMs (leukocytes, neutrophils, monocytes, thrombocytes, erythrocytes, hematocrit, hemoglobin, and high-sensitive CRP) and their linear association with indicators of the metabolic syndrome (according to a modified version of the US National Cholesterol Education Program Adult Treatment Panel III): HbA1c, non-fasting plasma glucose, body mass index, blood pressure, cholesterol, low-density lipoprotein, high-density lipoprotein, and triglycerides. With logistic regression, we calculated odds ratios (ORs) of metabolic syndrome in individuals with increased levels of CIMs compared to individuals with normal levels based on current Danish reference ranges. RESULTS In general, there was a positive correlation between most CIMs and indicators of the metabolic syndrome both in the age-sex-adjusted and multivariable linear regression analyses. In the age-sex-adjusted logistic regression analyses, increased levels of all CIMs were associated with increased prevalence of dyslipidemia (OR: 1.4-2.2), hypertension (OR: 1.3-3.1), diabetes mellitus (OR: 1.5-3.4), obesity (1.4-4.6), and the metabolic syndrome (OR: 1.4-2.8). However, neutrophils and thrombocytes were not significant when it came to hypertension and diabetes mellitus, respectively (Table 1). DISCUSSION & CONCLUSION In this study we examined the association between different CIMs and a wide variety of metabolic changes. To our knowledge it is the first comprehensive epidemiological study linking the phenotypical presentation of MPNs in a general population of more than 20.000 individuals with a broad spectrum of metabolic disturbances. With chronic inflammation being proposed as a trigger and consequence of both MPNs and metabolic syndrome and considering the results in the present study it is intriguing to postulate chronic inflammation as the common denominator in both metabolic syndrome leading to MPNs and MPNs leading to metabolic syndrome(Figure 1). It is of great clinical interest to investigate if an increased risk of metabolic syndrome exists in e.g. a cohort of MPN patients and whether people with incident metabolic syndrome have increased risk of MPNs and second cancer. An increased prevalence of a wide variety of metabolic disturbances following increased CIMs could potentially, if similar results are found in the MPN population, support a future change in the MPN-risk stratification. Amongst the tested CIMs only thrombocytes (> 1500 Mia/L) are currently used as a risk factor. In conclusion, elevated levels of CIMs were associated with an increased prevalence of metabolic disturbances. Our results substantiate the need for similar studies in MPN patients, being characterized by chronic inflammation and elevated cell counts. Disclosures Hasselbalch: Novartis: Research Funding.

Background: Secondary CNS involvement (SCNS) is a detrimental complication seen in ~5% of patients with diffuse large B-cell lymphoma (DLBCL) treated with modern immunochemotherapy. Data from older series report short survival following SCNS, typically lt;6 months. However, data in patients that develop SCNS following primary therapy that contains a rituximab-based-regimen as well as the impact of more intensified treatment for SCNS are limited.Aims: The aims of this study were to i) describe the natural history of SCNS in a large cohort of patients treated with immunochemotherapy, and ii) determine prognostic factors after SCNS.Patients and methods: We performed a retrospective study of patients diagnosed with SCNS during or after frontline immunochemotherapy (R-CHOP or equivalently effective regimens). SCNS was defined as new involvement of the CNS (parenchymal, leptomeningeal, and/or eye) in patients without known CNS involvement at the time of first pathologic diagnosis of DLBCL. Patients were identified from local databases and/or regional/national registries in Denmark, Canada (British Columbia), Australia, Israel, US (University of Iowa/Mayo Clinic SPORE), and England (Guy's and St. Thomas' Hospital, London). Clinico-pathologic and treatment characteristics at the time of SCNS were collected from medical records.Results: In total, 281 patients with SCNS diagnosed between 2001 and 2016 were included. Median age at SCNS was 64 (range 20-93) years and male:female ratio was 1.3. SCNS occurred as part of first relapse in 244 (87 patients and 112 (40 had documented concurrent systemic disease at the time of SCNS. The median time from initial DLBCL diagnosis to SCNS was 9 months, which was similar for patients treated with (N=76, 27 or without upfront CNS prophylaxis (N=205, 73 (10 vs 9 Mo; P=0.3). The median post-SCNS OS was 4 months (interquartile range 2-13) and the 2yr survival rate was 20% (95% CI 15-25) for the entire cohort. Associations between clinicopathologic features, management strategy, and post-SCNS survival are shown in Table 1, which excludes patients who did not receive any treatment against SCNS, patients treated with steroids alone, and a patient with unavailable treatment information (n=43, 15. In multivariable analysis, performance status gt;1, concurrent leptomeningeal and parenchymal involvement, SCNS developing before completion of 1st line treatment, and combined systemic and CNS involvement by DLBCL were associated with inferior outcomes. Upfront CNS prophylaxis did not influence post-SCNS OS. High-dose methotrexate (HDMTX) and/or platinum based treatment regimens (i.e. ICE, DHAP, or GDP [+/- IT treatment and/or radiotherapy], N=163) for SCNS were associated with reduced risk of death (HR 0.45 [0.32-0.62, Plt;0.01]). The 2yr post-SCNS survival for patients treated with HDMTX and/or platinum-based regimens (N=163) was 29% (95% CI 22-37). For patients with isolated parenchymal SCNS, single modality treatment with radiotherapy resulted in 2-yr OS of 19% (95% CI 8-35). For the subgroup of 49 patients treated with HDMTX- and/or platinum-based regimens for isolated SCNS after 1st line DLBCL treatment and with performance status 0 or 1, the 2yr post-SCNS survival was 46% (95% CI 31-59). Overall, 9% of the patients received HDT with ASCT as part of salvage therapy at the time of SCNS. Amongst 36 SCNS patients without systemic involvement and in CR following intensive treatment (HDMTX and/or platinum-based treatments), 11 patients consolidated with HDT had similar outcomes to 25 patients treated without consolidating HDT (P=0.9, Fig 1)Conclusions: Outcomes for patients with SCNS remain poor in this large international cohort of patients from the immunochemotherapy era. Combined parenchymal and leptomeningeal disease, presence of systemic disease concurrent with SCNS, performance status gt;1, and SCNS developing during first line treatment were independently associated with inferior OS. However, a significant fraction of patients with isolated SCNS after first line DLBCL treatment and with good performance status may achieve long-term remissions after intensive regimens for SCNS.Disclosures El-Galaly: Roche: Consultancy, Other: travel funding. Cheah: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Other: Speaker's Bureau. Kansara: Celgene: Honoraria. Connors: Bristol Myers Squib: Research Funding; NanoString Technologies: Research Funding; F Hoffmann-La Roche: Research Funding; Millennium Takeda: Research Funding; Seattle Genetics: Research Funding. Sehn: roche/genentech: Consultancy, Honoraria; amgen: Consultancy, Honoraria; seattle genetics: Consultancy, Honoraria; abbvie: Consultancy, Honoraria; TG therapeutics: Consultancy, Honoraria; celgene: Consultancy, Honoraria; lundbeck: Consultancy, Honoraria; janssen: Consultancy, Honoraria. Opat: Roche: Consultancy, Honoraria, Other: Provision of subsidised drugs, Research Funding. Seymour: Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Villa: Celgene: Honoraria; Lundbeck: Honoraria; Roche: Honoraria, Research Funding.↵* Asterisk with author names denotes non-ASH members.

Background: Secondary CNS involvement (SCNS) is a detrimental complication seen in ~5% of patients with diffuse large B-cell lymphoma (DLBCL) treated with modern immunochemotherapy. Data from older series report short survival following SCNS, typically Aims: The aims of this study were to i) describe the natural history of SCNS in a large cohort of patients treated with immunochemotherapy, and ii) determine prognostic factors after SCNS. Patients and methods: We performed a retrospective study of patients diagnosed with SCNS during or after frontline immunochemotherapy (R-CHOP or equivalently effective regimens). SCNS was defined as new involvement of the CNS (parenchymal, leptomeningeal, and/or eye) in patients without known CNS involvement at the time of first pathologic diagnosis of DLBCL. Patients were identified from local databases and/or regional/national registries in Denmark, Canada (British Columbia), Australia, Israel, US (University of Iowa/Mayo Clinic SPORE), and England (Guy's and St. Thomas' Hospital, London). Clinico-pathologic and treatment characteristics at the time of SCNS were collected from medical records. Results: In total, 281 patients with SCNS diagnosed between 2001 and 2016 were included. Median age at SCNS was 64 (range 20-93) years and male:female ratio was 1.3. SCNS occurred as part of first relapse in 244 (87%) patients and 112 (40%) had documented concurrent systemic disease at the time of SCNS. The median time from initial DLBCL diagnosis to SCNS was 9 months, which was similar for patients treated with (N=76, 27%) or without upfront CNS prophylaxis (N=205, 73%) (10 vs 9 Mo; P=0.3). The median post-SCNS OS was 4 months (interquartile range 2-13) and the 2yr survival rate was 20% (95% CI 15-25) for the entire cohort. Associations between clinicopathologic features, management strategy, and post-SCNS survival are shown in Table 1, which excludes patients who did not receive any treatment against SCNS, patients treated with steroids alone, and a patient with unavailable treatment information (n=43, 15%). In multivariable analysis, performance status >1, concurrent leptomeningeal and parenchymal involvement, SCNS developing before completion of 1st line treatment, and combined systemic and CNS involvement by DLBCL were associated with inferior outcomes. Upfront CNS prophylaxis did not influence post-SCNS OS. High-dose methotrexate (HDMTX) and/or platinum based treatment regimens (i.e. ICE, DHAP, or GDP [+/- IT treatment and/or radiotherapy], N=163) for SCNS were associated with reduced risk of death (HR 0.45 [0.32-0.62, P Conclusions: Outcomes for patients with SCNS remain poor in this large international cohort of patients from the immunochemotherapy era. Combined parenchymal and leptomeningeal disease, presence of systemic disease concurrent with SCNS, performance status >1, and SCNS developing during first line treatment were independently associated with inferior OS. However, a significant fraction of patients with isolated SCNS after first line DLBCL treatment and with good performance status may achieve long-term remissions after intensive regimens for SCNS. Disclosures El-Galaly: Roche: Consultancy, Other: travel funding. Cheah:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Other: Speaker's Bureau. Kansara:Celgene: Honoraria. Connors:Bristol Myers Squib: Research Funding; NanoString Technologies: Research Funding; F Hoffmann-La Roche: Research Funding; Millennium Takeda: Research Funding; Seattle Genetics: Research Funding. Sehn:roche/genentech: Consultancy, Honoraria; amgen: Consultancy, Honoraria; seattle genetics: Consultancy, Honoraria; abbvie: Consultancy, Honoraria; TG therapeutics: Consultancy, Honoraria; celgene: Consultancy, Honoraria; lundbeck: Consultancy, Honoraria; janssen: Consultancy, Honoraria. Opat:Roche: Consultancy, Honoraria, Other: Provision of subsidised drugs, Research Funding. Seymour:Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Villa:Celgene: Honoraria; Lundbeck: Honoraria; Roche: Honoraria, Research Funding.

Background Central nervous system (CNS) relapse in patients with diffuse large B-cell lymphoma (DLBCL) is an infrequent but devastating complication. The German Risk model which includes the 5 IPI risk factors plus involvement of the kidneys has been validated in 2 large independent cohorts (Schmitz, ICML 2013; Savage, ASH 2014; El-Galaly, ICML 2015). In this model, the presence of >1 extranodal site of involvement contributes only 1 point. However, the precise impact of the extent of extranodal disease in PET-CT staged patients is unknown. Patients and Methods We identified patients with newly diagnosed DLBCL presenting to hospitals in Denmark, Canada, the United Kingdom and Australia through systematic searches of national/local lymphoma registries. Inclusion criteria were: staging included PET-CT, primary treatment with R-CHOP or similar regimen ± CNS prophylaxis. Patients treated with high-dose regimens (such as R-HyperCVAD) and those with CNS involvement at diagnosis were excluded. Medical records and PET-CT reports were reviewed for clinical information and outcome. Multiple lesions in one organ or set of paired organs/ tissue were counted as a single extranodal site, and the spleen and Waldeyer's ring were not included as extranodal sites. Time to CNS relapse was determined using the method of Kaplan and Meier, with univariate analysis of absolute number of extranodal sites associated with CNS relapse performed using competing risk regression with death before CNS relapse as competing risk. Multivariate analyses (adjusted for elevated LDH, age>60 y and performance status>1) were performed using Cox proportional hazards to identify the specific increase in risk attributable to the absolute number of extranodal sites of involvement. Involvement of the kidney/adrenals and advanced disease stage were not included in the adjustment because of their intrinsic relationship to number of extranodal sites. Results 1,536 patients meeting the above criteria were included, with the following characteristics: median age 65 y (range 17-92), 63% stage III/IV, 39% B symptoms, 50% elevated LDH, 15% performance status >1 and 39%, 36%, 15%, 6% and 3% had 0, 1, 2, 3 and 4+ extranodal sites of involvement, respectively. 79% received no specific CNS-directed prophylaxis; 8% received intrathecal chemotherapy alone, 5% received systemic high-dose anti-metabolites and 8% received both intrathecal and systemic. After a median follow-up of 41 (interquartile range 28-61) months, 62 (4%) patients developed CNS relapse at a median of 9 (range 4-78) months from initial diagnosis. The 3-y incidence of CNS relapse, unadjusted and adjusted hazard ratios for CNS relapse according to number of extranodal sites of involvement are presented in Table 1 . The competing risk regression analysis for CNS relapse using absolute number of extranodal sites of involvement is displayed in Figure 1 ; >2 vs 2 or fewer extranodal sites was associated with markedly increased risk of CNS progression ( P 60 y and performance status >1 ![Figure 1.][1] Figure 1. Competing risk regression analysis depicting cumulative incidence of CNS relapse according to absolute number of extranodal sites of involvement. Disclosures Hutchings: Takeda: Research Funding. Connors: Roche: Research Funding; Seattle Genetics: Research Funding. Seymour: Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Phebra: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Infinity: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Membership on an entity's Board of Directors or advisory committees. Villa: Roche: Research Funding. [1]: pending:yes

Introduction The discovery of mutations in the calreticulin (CALR) gene in the majority of JAK2 -V617F negative patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF) (Klampfl et al., 2013; Nangalia et al., 2013) has improved the diagnostic accuracy considerably, and most recently distinct clinical and hematological characteristics according to mutational status have been described (Park et al., 2015). The perspective is to personalize and optimize treatment according to the molecular and clinical landscape. This may be achieved by obtaining more information on responses in myeloproliferative neoplasms (MPN) to existing treatment strategies as assessed by the allele burden. Mutations in the CALR gene have proven to play a major role in oncogenic and immunologic processes (Lu, Weng, & Lee, 2015). In this context, it is highly relevant to explore the effectiveness of interferon-alpha2 (IFN) in reducing the CALR -mutated clone. Until now, only one paper has reported a decrease in allele burden in two patients during IFN treatment (Cassinat, Verger, & Kiladijan, 2014). The objective of this report is to expand current knowledge on this important topic by describing the mutant CALR allele burden over time in a larger group of IFN-treated patients. Method Clinical data were collected retrospectively from a single institution on all IFN-treated CALR positive MPN patients with sequential determinations of the mutant allele burden. Type 1 and type 2 mutations were initially identified by a previously published fragment analysis (Klampfl et al 2013). We have developed a Taqman qPCR assay for precise determination of the mutant allele burden of type 1 and type 2 mutations. Stored DNA was subsequently analysed to increase follow-up time. Results Twenty-one patients were included. Fifteen patients had a diagnosis of PMF; 7 of these were diagnosed with prefibrotic myelofibrosis. Six patients had ET. The type 1 and 2 mutations were found in 15 and 6 patients, respectively. Median age was 60 years (range 42-79) and the sex ratio (M/F) was 8/13. Fifteen patients (71%) were in ongoing treatment with IFN, whereas treatment was discontinued in 6 (29%) because of side effects. Median time of IFN treatment was 756 days (range 42-3927). The IFN prescribed was either subcutaneous injection of Pegasys® (median: 45 microgram (ug) per week), PegIntron® 25-50 ug per week, or Multiferon® 3 x 3 million IU per week. Median follow up time since the first CALR measurement was 756 days (range 294-2108). Fourteen patients (67%) maintained an unchanged allele burden during follow up; 1 patient (5%) presented a temporary decrease (from 39% to 27% in allele burden) but increased to the initial level within months while still on IFN treatment (presumably due to low compliance); 1 patient (5%) displayed an increase in allele burden during transformation to acute myelogenous leukemia (Figure 1); and 5 patients (24%) exhibited a marked decrease in allele burden (median decrease: 32%, range 18-45) during treatment with IFN (Figure 2). All 5 patients with decreasing allele burden (Table 1) normalized their platelet counts within a median time of 5 weeks (range 4-20) after initiating treatment with IFN. Conclusion Using a novel sensitive assay for the CALR mutant allele burden, we have demonstrated and substantiated the effectiveness of IFN to reduce the allele burden in a larger series of CALR positive patients with PMF and ET. Importantly, we report for the first time on highly heterogeneous response patterns. Our observation of one fourth of the CALR positive patients responding to treatment with IFN strongly suggests that IFN significantly influences the CALR mutational load. Further clinical and molecular studies are urgently needed to explore the mechanisms behind the heterogeneous response patterns and the clinical implications in regard to clonal evolution and disease progression in non-responding patients. We are currently analysing these issues to assess the definite role of IFN in future treatment strategies in CALR positive MPN patients. Table 1. Patients responding to interferon-alpha2 Characteristics Number/median (range) Patients 5 Age, years 53 (42-62) Sex (M/F) 1/4 Diagnosis- Essential thrombocythemia- Primary myelofibrosis- Prefibrotic myelofibrosis 221 Calreticulin mutation type- type 1- type 2 50 Duration of interferon-alpha2 treatment, days 960 (177-2790) Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Cordua: Janssen-Cilag: Other: travel grant. Off Label Use: interferon alpha2 for myeloproliferative neoplasms. Holmström:La Roche Ltd: Other: travel grant. Pallisgaard:Qiagen: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: travel grant, Speakers Bureau; Bristol Meyer Squibb: Speakers Bureau; Novartis: Other: travel grant, Research Funding, Speakers Bureau; Roche: Other: travel grant. Hasselbalch:Novartis: Research Funding.

Recent studies have shown the Philadelphia-negative myeloproliferative neoplasms (MPN) to be massively underdiagnosed and often preceded by a long pre-diagnostic phase of several years, in which many patients suffer serious vascular events. In this review, we focus on the urgent need for earlier diagnosis and treatment of MPN. Such efforts are foreseen to decrease morbidity and mortality for the individual patients and potentially reduce costs for health and social care systems.